The Iliad recounts 51 days of a 10-year war. The war started because Paris, a Trojan, kidnapped Helen, Agamemnon's wife. Paris kidnapped Helen, because Aphrodite promised him the most beautiful mortal woman. Aphrodite promised him the most beautiful mortal woman in order to win the beauty contest between her, Hera, and Athena. The beauty contest occurred because Eris (Strife), who had not been invited, threw a golden apple into the wedding party of Thetis and Peleus (Achilles' parents). The apple was labeled "for the fairest," and Athena, Aphrodite, and Hera claimed it. Zeus had Hermes bring them to Paris to judge the contest. Each goddess offered a bribe (so it was not about beauty after all!). Aphrodite won.
Paris is also called Alexander. When he was in his mother Hecuba's womb, she dreamt that she gave birth to a torch that lit Troy afire. Priam, her husband, thus abandoned the boy at birth in the wilderness on Mt. Ida. Shepherds found the boy and saved it, calling it "Alexander." When the boy came of age, men came from Troy to claim a bull from Paris' herd. The bull was to be the prize at funeral games being held in honor of the baby who had been exposed. Paris decided to enter the games and won. His unknowing brother Deiphobus drew a sword on him, but his sister Cassandra recognized him. Priam then acknowledged him and brought him back to Troy.
On winning the prize of the most beautiful mortal from Aphrodite, Paris abandoned his beloved Oenone and set out with his brother Aeneas for Sparta. There he met the Dioscuri, Helen's brothers, who introduced him to Menelaus, who soon left for a funeral on Crete. While he was gone, Paris won Helen's love, and she went back to Troy with him.
Paris later kills Achilles with an arrow, but himself is killed by Philoctetes by a poisoned arrow in the groin. Although Oenone had the antidote to the poison, she took pity on him too late and he died.
Before the Trojan war of the Iliad, Hercules went to war against Troy too.
The Trojan war ended when the Greeks pretended to leave and left behind a wooden horse with warriors inside. The Trojans brought it into their city, the warriors emerged at night and opened the gates, and Troy was sacked. After the war, the Greeks returned home. The Odyssey is the story of the return of Odysseus to his wife Penelope and his kingdom on Ithaca. Agamemnon notoriously returned to be killed by his wife and her lover (Aegisthus). Orestes and Electra, Agamemnon's offspring, then kill their mother and Aegisthus. Helen returns with Menelaus.
In general, most of the major figures in the Iliad are found elsewhere in Greek mythology. Although all the sources are later than Homer, nonetheless it is clear that the traditions reach far back in time, and it is likely that there were other epics, perhaps not as good, popular, or widespread as the Iliad and Odyssey.